Role of secretin and cholecystokinin in oleic acid-stimulated pancreatic secretion in rats

Variation in exocrine pancreatic secretion in rats due to different commercial diets

The diet fed to laboratory animals is one of many variables that can confound research results. The authors investigated the effect of the composition of commercial standard rodent diets on exocrine pancreatic function in rats. They compared two widely used commercial animal diets and found that diet composition greatly influences pancreatic secretion. Their results indicate that commercial diets should conform to the recommended composition requirements to avoid alterations in physiological functions that would eventually affect the results of biomedical research and that investigators should be keenly aware of the composition of the diets being fed to their animals.

Intestinal fat digestion plays a significant role in fat-induced suppression of gastric acid secretion and gastrin release in the rat

We have investigated the role of intestinal fat digestion in fat-induced suppression of gastric acid secretion and gastrin release in the rat. Intraduodenal administration of oleic acid (10%, pH 6.5) and triglyceride (10%, pH 6.5) at a rate of 2 ml/hr resulted in significant suppression of gastric acid secretion and gastrin release stimulated by intragastric perfusion of peptone (0.5%). Diversion of pancreatic juice from the duodenum completely abolished triglyceride-induced inhibition of peptone-stimulated gastric acid secretion and plasma gastrin release, but oleic acid-suppressed gastric acid secretion and gastrin release were unaffected by pancreatic juice diversion. Intraduodenal administration of digested triglyceride, prepared by preincubation with lipase, caused significant suppression of the peptone-induced gastric acid secretion and rise in plasma gastrin levels, even though pancreatic juice was excluded. The results of this study indicate that digestive products of triglyceride by pancreatic juice, especially by lipase, are responsible for the intestinal fat-induced inhibition of gastric acid secretion and gastrin release and that intestinal fat digestion plays a significant role in the mechanism.

Role of endogenous secretin and cholecystokinin in intraduodenal oleic acid-induced inhibition of gastric acid secretion in rats

We investigated a possible role of endogenous secretin and cholecystokinin (CCK) in inhibition of gastric acid secretion induced by intraduodenal administration of oleic acid in rats. Intraduodenal administration of oleic acid emulsion in a dose of 1 mmol/hr resulted in significant inhibition of gastric acid secretion stimulated by intravenous infusion of pentagastrin (0.3 micrograms/kg/hr), and this was accompanied by an increase in the plasma concentration of both secretin and CCK, from 1.2 +/- 0.08 pM and 20.6 +/- 1.2 pM to 4.3 +/- 0.18 pM and 31.6 +/- 0.9 pM, respectively (P less than 0.001). Intravenous infusion of secretin (0.05 CU/kg/hr) inhibited pentagastrin-stimulated gastric acid secretion, but CCK-8 (0.03 micrograms/kg/hr) failed, although intravenous infusion of secretin and CCK in those doses produced plasma levels comparable to the levels achieved in response to oleic acid administration. Furthermore, the oleic acid-induced suppression of gastric acid secretion was blocked significantly by intravenous injection of rabbit anti-secretin serum (0.1 ml), but not by intravenous infusion of a CCK-receptor antagonist, CR 1409 (5 mg/kg/hr). Thus, the results of this study indicate that endogenous secretin rather than CCK is involved in the hormonal mechanism regulating the inhibition of gastric acid secretion by intestinal fat in rats.